Regulating apparatus for a hydraulic track spreader



1967 H. HAUSENBLAS ETAL 3,360,063

REGULATING APPARATUS FOR A HYDRAULIC TRACK SPREADER Filed June 27, 19664 Sheets-Sheet 1 FIG] INVENTORS HELMUT HAUSENBLAS EWALD- POPPE HANSMASSHOLDER ATTOR Y w Fiied June 27, 1966 1967 A H. HAUSENBLAS ETAL 3, 53

REGULATING APPARATUS FOR A HYDRAULIC TRACK SPREADER 4 Sheets-Sheet 2FIG. 2

mmvrons HELMUT HAUSENBLAS EWALD POPPE BY HANS MASSHOLDER Filed June 27,1966 6 H. HAUSENBLAS ETAL 3,360,

REGULATING APPARATUS FOR A HYDRAULIC TRACK SPREADER 4 Sheets-Sheet 4mmvroxs HELMUTHAUSENBLAS EWALD POPPE BY HANS MASSHOLDER United StatesPatent 3,360,063 REGULATING APPARATUS FOR A HYDRAULIC TRACK SPREADERHelmut Hausenblas, Kassel, Ewald Poppe, Overvellmar, and HansMassholder, Kassel, Germany, assignors to Rheinstahi Henschel A.G.,Kassel, Germany, a corporation of Germany Filed June 27, 1966, Ser. No.560,414 Claims priority, application Germany, Jan. 15, 1966, R 42,427 6Claims. (Cl. 180-92) This invention relates to a regulating apparatusfor, and method for regulating, a track adjuster used on a trackedvehicle.

In one known construction of hydraulic track adjusters for a trackedvehicle, the force with which the reversing roller is urged against thetrack is maintained at a constant value, independent of the position ofthe reversing roller and also of the track adjuster, by means of aregulating system for maintaining a constant pressure of the hydraulicfluid in the track adjuster cylinder. This has the disadvantage that,during particular driving conditions which require a low advancing forceor power in the more tightly stretched portions of the track between thedriving sprocket and that portion of the track resting on the surface ofthe road or other surface, the track is stretched or tightenedexcessively. On the other hand, driving conditions also may occur, forexample over mountainous terrain, which require such a great advancingforce that the track adjuster force being regulated in this manner doesnot sufiice to prevent the track adjuster from running into theinnermost position thereof due to the longitudinal track forces actingon the reversing roller.

In another known construction of hydraulic track adjusters, the supplyof the hydraulic fluid to and from the track adjuster cylinder iscontrolled by appropriate valves or slides, or by a combined valve andslide, in such a manner that the hydraulic fluid can flow to the trackadjuster under the predetermined line feed pressure if the forcesexerted by the track on the reversing roller are small. If thelongitudinal track tension or force increases beyond the valuecorresponding to the hydraulic line feed pressure, the inflow of thehydraulic fluid is blocked but no outlet is opened. The pressure of thehydraulic in the track adjuster then will increase corresponding to thelongitudinal track force until a predetermined upper safety limitingvalue has been attained, at which point an outlet will be opened. Thedisadvantage of this particular construction is that, after thelongitudinal track force corresponding to the feed pressure has beenexceeded, the track adjuster can not start but will, instead, moveslightly inwardly due to the compressibility of the hydraulic fluid.This disadvantage becomes particularly evident if the traveling ordriving direction is such that the more strongly tightened or stretchedtrack portion between the driving sprocket and the track part resting onthe surface of the road runs over the reversing roller.

An excessive tension in the track results in excessively high losses ofthe driving force or propulsive output, whereas a tension which is toolow may, under certain circumstances, produce a breaking of the track.In general, therefore, it is desirable to tighten or spread the track ineach case to such an extent that neither of these two difficulties willresult. Thus, it is desired to correlate the force with which thereversing roller is rged against the track in each case to the advancingor driving force required by the vehicle at the particular track. It isknown to achieve this in an approximate manner in which the theoreticalvalue of the hydraulic.

fluid pressure which should exist in the track adjuster cylinder ismanually adjustable in either two or more stages. It also has beenproposed to measure the torque in the track drive, which is proportionalto the advancing force of the track, i.e., to measure it in the elementsfor the transmission of power connected to the trackdriving sprocket andto determine therefrom the reference input, i.e., the theoretical value,for the aforementioned hydraulic pressure.

The present invention utilizes in a particularly advantageous manner thelatter regulation of hydraulic pressure within the track adjustercylinder. For this purpose, the present invention utilizes knowntransmitting elements, for example, those of electrical, electronic,hydraulic, or purely mechanical types, which transform or convert thetorque measured at the track-driving sprocket into the reference inputfor the hydraulic pressure in the track adjuster cylinder, and transmitthe same to the corresponding cylinder, the transmitting element beingso constructed that the following correlation is produced between thedriving torque and the reference input for the aforementioned hydraulicpressure: (a) In the case of driving conditions in which that portion ofthe track over-running the reversing roller participates in thetransmission of the tractive force from the driving sprocket to the roadsurface, the reference input of the hydraulic pressure in the trackadjuster cylinder results in a longitudinal track force within the twoparts of the track running off the reversing roller which is at alltimes by a precisely constant or substantially constant value above theadvancing force or power transmitted by the respective track to the roadsurface and, (b) In driving conditions in which that portion of thetrack over-running the reversing roller does not participate in thetransmission of the tractive force from the track-driving sprocket tothe road surface, the reference input of the hydraulic pressure in thetrack adjuster cylinder results in a precisely constant or substantiallyconstant longitudinal track force in the two parts of the track runningoff the reversing roller which is preferably equal to the constantexcess value referred to under (a) above.

The measurement of the driving torque, supplied to the driving sprocketwhich is necessary for the regulation of the hydraulic pressure in thetrack adjuster cylinder, may be performed particularly favorably if thetrack drive is equipped, in known manner, with a planetary-typereduction gear. In such case, it is preferred that the supporting orhearing moment of the stationary part of the planetary gear, generallythe outer ring, be measured with known means.

One embodiment of the present invention is illustrated in theaccompanying drawings in which:

FIGURE 1 is a schematic view showing the principle of a track with theratios of forces prevailing therein in one driving direction,

FIGURE 2 is a corresponding schematic view for the opposite drivingdirection,

FIGURE 3 is a diagram of the ratios of forces prevailing at thereversing roller,

FIGURE 4 is a flow diagram of the signal arrangement employed in thepresent invention,

FIGURE 5 is a graphic representation of the dependence of the trackadjuster force on the advancing force which the track transmits to theroad,

FIGURE 6 is a diagram of a track drive with a sun and planet gear,

FIGURE 7 is a schematic top plan view of the sun and planet gear of thetrack drive with means for measurement of the torque, and

FIGURE 8 is a schematic view of a measuring member for measurement ofthe torque.

In FIGURES 1 and 2, reference numerals 1 to 1 designate the road wheels,reference numeral 2 identifies the driving sprocket, reference numeral 3identifies the reversing roller, and reference numeral 41 identifies thetrack. Reference numeral 5 identifies the piston, reference numeral 6designates the piston rod, and reference numeral 7 represents thecylinder of the hydraulic track adjuster in which force is produced bythe pressure of the hydraulic fiuid within the cylinder space 8. Thelongitudinal forces in the track for the driving direction according tothe arrow 9 have been indicated in FIGURE 1 and for the drivingdirection according to the arrow 9 in FIGURE 2 by means of lines appliedin each case at a right angle to the track 4. The advancing power orforce Z and Z respectively has been shown therein, in the interest ofsirniplification, as being transmitted to the track 4 in a uniformlydistributed manner to the road surface, not shown. It was furtherassumed, also in the interest of simplification, that this force istransmitter at the first tooth of the driving sprocket 2 in engagementwith the track 4 and is transmitted undiminished. The arrows M in FIGURE1 and M in FIGURE 2 indicate the direction of the torque at the drivingsprocket. The slack strand of the track must not be completely withouttension but should have a slight pretensioning force P and Prespectively, in order to ensure a faultless running-off of the track.Accordingly, the strand of the track revolving around the reversingroller has, in FIG- URE 1, the longitudinal track force P -=Z +P and, inFIGURE 2, the longitudinal track force P From these longitudinal trackforces, which have been generally designated by P in FIGURE 3, results,in known manner, the track adjuster force P which is required tocounteract the track force, note FIGURE 3. In this instance, only thesimple case was assumed where the track adjuster is positioned preciselyin the direction of the resultant P Otherwise, P must be determined fromP using the known laws of mechanics, for example, if the reversingroller is mounted on a crank arm, by means of the equations of moments.

In the signal fiow diagram of FIGURE 4, reference numeral 11 representsthe device for measuring the torque applied to the driving sprocket 2,reference numeral 12 identifies the converter, which may beelectronically operated for example, for producing the reference inputfor the hydraulic pressure within the cylinder space 8 of the trackadjuster cylinder '7; reference numeral 13 identifies the regulator ofthis hydraulic pressure, and reference numeral 14 represents the controlelement, e.g., a distributing slide valve for the hydraulic fluid.Reference numeral 15 represents the cylinder space 8 of the trackadjuster cylinder 7.

The supply of hydraulic fluid to the control element 14 is effected at16 from a supply system, not shown, and the discharge from the element14 is effected at 17 to a reservoir, not shown. Transmitted at 18 arethe measured values for the driving torque M and M respectively,according to value and sign, at 19 the reference input for the hydraulicpressure in the track adjuster cylinder 15, being formed in 12, at 20the displacing movement of the control element 14, and at 21 thehydraulic fluid flow either to or from the track adjuster cylinder 15.The repeating or answering signal of the actual value of the hydraulicpressure in 15 to the regulator 13 is effected at 22.

FIGURE 5 illustrates the characteristics 24 and 25 of the member 12. Theadvancing forces Z and Z respectively, being transmitted by the track tothe road are shown as the abscissa for the driving directions accordingto FIGURES 1 and 2, respectively. The instrument 12 indicates the forcesZ and Z from the measured values for the driving torque M and Mrespectively, by multiplication with the corresponding constant. Theordinate is the track adjuster force P and also the hydraulic pressurein the track adjuster cylinder, which is proportional thereto. The trackadjuster force portion Pkg and also the dashed line 23 correspond to thedriving condition of FIGURE 1, but for the undesirable case where P '=O.The angle 5 of this line is found by means of known correlations fromthe angle a of FIGURE 3. In order to obtain the desired finite value ofP the characteristic 24 is positioned over the line 23 by acorresponding value P so that for the driving conditions of FIGURE 1,the hydraulic pressure in the track adjuster cylinder is regulated inaccordance with the track adjuster force P For the driving conditionsaccording to FIGURE 2, there results from the requirement of thespecific value for P the track adjuster force P In the track driveaccording to FIGURES 6 and 7, reference numeral 30 designates the driveshaft originating from the steering mechanism, reference numeral 31identifies the sun gear rigidly secured thereto and reference numerals32; to 32 represent the planet gears which are mounted on the planetcarrier 33, the latter being connected to the track-driving sprocket 35by means of the shaft 34. Reference numeral 36 identifies the outer gearring of the planetary gear, which is secured against rotation by meansof the measuring members, preferably three, 37 to 37 connected to thevehicle hull at as, to 38 respectively. The measuring members 37 whichmeasure the moment of the outer ring 36, which moment is proportional tothe torque at the driving sprocket 35, may be constructed, for example,according to FIGURE 8. As shown in the latter figure, they may consistof a slightly resilient ring 40 with two straps 41 and 42, with the aidof which the measuring members are secured to the gear ring 36 and alsoto the vehicle hull. The force measurement is effected by determiningthe deformation of the ring 41) by means, for example, of an inductivepath recorder 43 which is responsive to the change of the ring diameterbetween the straps 41 and 42. Other constructions of the measuringmember which may be employed are traction-compression rods withextension measuring strips secured thereto, or hydraulic cylinders, thepressure of the hydraulic fluid serving as an indication of the bearingpower or force.

It will be obvious to those skilled in the art that many modificationsmay be made within the scope of the present invention without departingfrom the spirit thereof, and the invention includes all suchmodifications.

What is claimed is:

1, An apparatus for regulating a hydraulic track adjuster for a trackedvehicle which comprises means for measuring the driving torque appliedto the track, and converter means connected thereto for producing areference input for the regulation of the hydraulic pressure in theadjuster cylinder in accordance with a characteristic wherein (a) fordriving conditions in which the track part over-running the reversingroller participates in the transmission of the tractive force from thetrack drive to the road surface, the reference input corresponds to alongitudinal force within the two parts of the track running off thereversing roller which is at all times in excess of, by an at leastsubstantialy constant value, the driving force transmitted to the roadby the track; and (b) for driving conditions in which the track partoverrunning the reversing roller does not participate in thetransmission of the tractive force from the track drive to the roadsurface, the reference input corresponds to an at least substantiallyconstant longitudinal force in the two parts of the track running offthe reversing roller which is substantially equal to the aforementionedexcess value.

2. An apparatus according to claim 1 in which the means for measuringthe driving torques applied to the track measure the retaining torquesof the stationary gear of a planetary gear system, which latter are partof driving means for a track-driving sprocket.

3. An apparatus according to claim 2 in which the measuring meansconnected to the stationary gear, comprises respectively at least oneresilient ring means having means connected thereto for measuringdifferences in the resilient ring diameter.

4. An apparatus according to claim 2 in which the measuring meansconnected to the stationary gear ring comprises respectively at leastone traction-compression rod containing strain gauges.

5. An apparatus according to claim 2 in which the measuring meansconnected to the stationary gear ring comprises at least one hydrauliccylinder containing measuring means for measuring the hydraulic pressurethere- 1n.

6. A method for regulating a hydraulic track adjuster for a trackedvehicle which comprises measuring the driving torque applied to thetrack and converting the obtained measurement into a reference input forthe regulation of the hydraulic pressure in the adjuster cylinder inaccordance with a characteristic wherein (a) for driving conditions inwhich the track part over-running the reversing roller participates inthe transmission of the trac tive force from the track drive to a roadsurface, the reference input corresponds to a longitudinal force withinthe two parts of the track running 01f the reversing roller which is atall times in excess of, by an at least substantially constant value, theadvancing force transmitted to the road by the track; and (b) fordriving conditions in which the track part over-running the reversingroller does not participate in the transmission of the tractive forcefrom the track drive to the road surface, the reference inputcorresponds to an at least substantially constant longitudinal force inthe two parts of the track running off the reversing roller which issubstantially equal to the aforementioned excess value.

References Cited UNITED STATES PATENTS 2,722,280 11/1955 Ballu 30510 X2,818,313 12/1957 Ashley 30510 2,998,998 9/1961 Hyler 305-10 X 3,082,0433/1963 Orton 305-10 3,187,674 6/ 1965 Hamrnelmann 74242.9 X 3,310,1273/1967 Siber 305-10 X RICHARD J. JOHNSON, Primary Examiner.

1. AN APPARATUS FOR REGULATING A HYDRAULIC TRACK ADJUSTER FOR A TRACKEDVEHICLE WHICH COMPRISES MEANS FOR MEASURING THE DRIVING TORQUE APPLIEDTO THE TRACK, AND CONVERTER MEANS CONNECTED THERETO FOR PRODUCING AREFERENCE INPUT FOR THE REGULATION OF THE HYDRAULIC PRESSURE IN THEADJUSTER CYLINDER IN ACCORDANCE WITH A CHARACTERISTIC WHEREIN (A) FORDRIVING CONDITIONS IN WHICH THE TRACK PART OVER-RUNNING THE REVERSINGROLLER PARTICIPATES IN THE TRANSMISSION OF THE TRACTIVE FORCE FROM THETRACK DRIVE TO THE ROAD SURFACE, THE REFERENCE INPUT CORRESPONDS TO ALONGITUDINAL FORCE WITHIN THE TWO PARTS OF THE TRACK RUNNING OFF THEREVERSING ROLLER WHICH IS AT ALL TIMES IN EXCESS OF, BY AN AT LEASTSUBSTANTIALY CONSTANT VALUE, THE DRIVING FORCE TRANSMITTED TO THE ROADBY THE TRACK; AND (B) FOR DRIVING CONDITIONS IN WHICH THE TRACK PARTOVERRUNNING THE REVERSING ROLLER DOES NOT PARTICIPATE IN THETRANSMISSION OF THE TRACTIVE FORCE FROM THE TRACK DRIVE TO THE ROADSURFACE, THE REFERENCE INPUT CORRESPONDS TO AN AT LEAST SUBSTANTIALLYCONSTANT LONGITUDINAL FORCE IN THE TWO PARTS OF THE TRACK RUNNING OFFTHE REVERSING ROLLER WHICH IS SUBSTANTIALLY EQUAL TO THE AFOREMENTIONEDEXCESS VALUE.